A process for manufacturing semiconductor devices from a wafer includes various processing steps, and each of the processing steps is performed on the wafer mounted on a mounting table. An alignment operation for precisely positioning the wafer is often performed prior to a specific processing step to be performed on the wafer.
In case a wafer is inspected by an inspection apparatus shown in FIG. 5 for example, the alignment between a plurality of test electrodes of each device of the wafer and probes corresponding thereto is performed before the inspection is carried out by allowing electrical contact between the test electrodes and the corresponding probes. As illustrated in FIGS. 5A and 5B, the inspection apparatus includes a loader chamber 1 for loading and unloading of a wafer W; and a prober chamber 2 for inspecting electrical characteristics of the wafer W. The loader chamber 1 has a transfer arm 3 for transferring a wafer W in a cassette C to the prober chamber 2; and a pre-alignment mechanism 4 for performing a pre-alignment of the wafer W while the wafer W is being transferred by the transfer arm 3.
The prober chamber 2 has a mounting table 5 for mounting thereon the pre-aligned wafer W, the mounting table 5 being movable in X, Y, Z and θ directions; a probe card 6 disposed above the mounting table 5; and an alignment mechanism 7 for performing an alignment between a plurality of probes 6A of the probe card 6 and the wafer W on the mounting table 5. The probe chamber 2 is operated under the control of a controller (not shown). Further, the probe card 6 is fixed at an opening of a head plate 8. A test head T is provided on top of the head plate 8, and the probe card 6 is electrically connected with a tester (not illustrated) via the head plate 8.
The pre-alignment mechanism 4 has a rotatable table 4A for mounting thereon the wafer W; and an optical detection unit (not shown) for optically detecting orientation flats and notches formed around an outer periphery of the wafer W. While the rotatable table 4A having thereon the wafer W is rotating, the optical detection unit detects the orientation flats and the notches of the wafer W, thereby pre-aligning the wafer in a specific direction.
As depicted in FIGS. 5A and 5B, the alignment mechanism 7 has a first CCD camera 7A, attached to the side of the mounting table 5, for capturing images of the probes 6A; a second CCD camera 7B for capturing images of the wafer W; and an alignment bridge 7C for supporting the second CCD camera 7B; and a pair of guide rails 7D for guiding the alignment bridge 7C to a probe center. The first CCD camera 7A captures the images of the probes 6A, and the second CCD camera 7B captures the images of the test electrodes of the wafer W. Next, the probes 6A and the test electrodes are aligned based on the image position data.
Meanwhile, prior to the alignment between the probes 6A and the wafer W, position data and the like which are obtained by capturing images of tips of specific probe 6A and a test electrodes of the wafer W by using the first and the second CCD camera 7A and 7B needs to be are registered. The registration is carried out by using the captured images of the probes 6A and the wafer W which are displayed on multi-windows of a display screen 9 of a display unit and a manipulation panel adjacent thereto. For example, the position data of the probes 6A positioned in four corners of the probe card 6 are registered according to the sequence shown in FIG. 6 by using the captured images displayed on the display screen 9 and the manipulation panel. To do so, positions of the probe 6A are detected first by photographing the probe card 6 at a low magnification with the first CCD camera 7A. Next, images of the tips of the probes 6A are captured at a high magnification. The obtained data is registered for alignment process.
First of all, the mounting table 5 automatically moves so that the first CCD camera 7A can be positioned at the probe center (center of the probe card 6) under the control of the controller. Next, the first CCD camera 7A captures an image of the probe card 6 at a low magnification from the probe 6A side. The captured image is displayed on the display screen 9 so that an overall state of the probe card 6 can be monitored. Then, the manipulation panel is manipulated to move the mounting table 5 from the probe center to a specific probe 6A while monitoring the captured image displayed on the display screen 9. When a focus of the first CCD camera 7A is aligned with a needle-tip of the probe 6A, view and illuminance of the first CCD camera 7A (hereinafter, referred to as “photographing conditions”) are selected. The selected photographing conditions and position data of the mounting table 5 obtained at this time are registered as first image information of a first macro node (step S1).
Next, the manipulation panel is manipulated to move the mounting table 5 in the same manner. When the first CCD camera 7A is focused on the tip of another probe 6A different from the probe 6A of the first macro node, photographing conditions are selected. The selected photographic conditions and position data of the mounting table 5 obtained at this time are registered as first image information of a second macro point (step S2).
Next, the first CCD camera 7A moves to still another probe 6A by the mounting table 5; In the same manner, photographing conditions and position data of the tip of the corresponding probe 6A are registered as first image information of a third macro point (step S3). Thereafter, photographing conditions and position data of the tip of a next probe 6A are registered in the same manner described above as first image information of a fourth macro point (step S4).
As described above, the images of the four probes 6A are captured as the first to the fourth macro point at a low magnification and the first image information of the first to the fourth macro point are registered. Thereafter, the first CCD camera 7A is switched to a high magnification employed in alignment. Then the first CCD camera 7A automatically moves by the mounting table 5 based on the position data of the first macro point. After the first CCD camera 7A is focused on the tip of the probe 6A corresponding to the first macro point, the photographing conditions at this time are selected as those for a first micro point. The selected photographing conditions and the position data obtained at this time are registered as second image information of the first micro point (step S5).
Thereafter, the first CCD camera 7A automatically moves by the mounting table 5 based on the position data of the second macro point. When the first CCD camera 7A is focused on the tip of the probe 6A corresponding to the second macro point, the photographing conditions at this time are selected as those for a second micro point. The selected photographing conditions and the position data obtained at this time are registered as second image information of the second micro point (step S6).
Next, the mounting table 5 automatically moves to the third macro point, and the probe 6A is photographed as a third micro point by the first CCD camera 7A. The photographing conditions and the position data obtained at this time are registered as the second image information of the third macro node (step S7). Then, the mounting table 5 automatically moves to the fourth macro point, and the probe 6A is photographed as the fourth micro point by the first CCD camera 7A. The photographing conditions and the position data obtained at this time are registered as second image information of the fourth micro point (step S8). A series of the probe registration operation is completed in this way, and the data obtained therefrom is provided for the alignment with the wafer W.
Further, photographing conditions and position data for multiple locations of the wafer W are also registered in a same manner as in the case of the probe 6A. Then, the probes 6A and the wafer W are aligned by using the registered data. Thereafter, electrical characteristics of a plurality of devices formed on the wafer W are inspected while index-feeding the wafer W.
While the electrical characteristic inspection is repeatedly performed on the same wafers W, the probe card 6 that has been used may be replaced with another probe card 6 of a different kind. In that case, even if the probe card 6 is functionally substantially identical to the old one, probes 6A of the new probe card 6 may have shapes different from those of the old one since the old and new probe cards are of different kinds. Thus, the probe 6A of the new probe card 6 may have images different from those of the old probe card 6 and the changed captured images may not be unrecognized by a computer. Accordingly, the new probe card 6 needs to be re-registered. The re-registration operation is also required when the probe card 6 has been contaminated. In order to perform the re-registration operation by using the conventional method, the entire processes described in FIG. 6 need to be performed, which requires a long period of time. Further, in case a pre-treatment performed on a wafer W has changed for example, re-registration needs to be performed with respect to the wafer W even though the wafer W remains substantially unchanged and a long period of time is required for the re-registration operation.